1. Field of the Present Invention
The present invention relates to a pattern forming method, an actinic-ray-sensitive or radiation-sensitive resin composition, and a resist film used for the pattern forming method. More specifically, the present invention relates to a pattern forming method suitable for a production process of a semiconductor such as an IC, a production process of a circuit board of a liquid crystal, a thermal head, or the like, and other lithography processes of photofabrication, and relates to an actinic-ray-sensitive or radiation-sensitive resin composition and a resist film used for the pattern forming method. Particularly, the present invention relates to a pattern forming method suitable for the exposure performed by an ArF exposure apparatus or an ArF liquid immersion projection exposure apparatus that uses far-ultraviolet rays having a wavelength of 300 nm or less as a light source and an EUV exposure apparatus, and to an actinic-ray-sensitive or radiation-sensitive resin composition and a resist film used for the pattern forming method.
2. Description of the Related Art
Since a resist composition for a KrF excimer laser (248 nm) has been developed, a pattern forming method using chemical amplification has been used to compensate for desensitization caused by the light absorption of the resist composition. For example, in positive type chemical amplification, first, a photoacid-generating agent that is included in an exposed portion in a resist composition is degraded by being irradiated with light and generates an acid. Thereafter, in a process such as PEB (Post Exposure Bake), by the catalytic action of the generated acid, an alkali-insoluble group included in the resist composition is changed to an alkali-soluble group. Subsequently, development is performed using, for example, an alkaline solution. In this manner, the exposed portion is removed, and a desired pattern is obtained.
In the above method, various alkaline developers have been suggested, and for example, an aqueous alkaline developer such as 2.38% by mass of aqueous TMAH (tetramethylammonium hydroxide) solution is widely used.
In addition, from the viewpoint of the improvement of a pattern forming performance such as the improvement of the resolution in the above positive type chemical amplification, an attempt to provide a group degraded by an acid in the photoacid-generating agent has been made (for example, see JP3606291B). Moreover, an attempt to add a photoacid-generating agent that has a polymerizable or crosslinkable group to the resist composition has been made (for example, see JP2007-65353A, JP2008-81470A, and JP2010-39483A).
In order to miniaturize semiconductor elements, the wavelength of an exposure light source is being shortened, and a projection lens with a high numerical aperture (high NA) is being made. Currently, an exposure machine using an ArF excimer having a wavelength of 193 nm as a light source has been developed. As a technique for further improving resolving power, a method (that is, liquid immersion) of filling a liquid (also referred to as a “liquid for liquid immersion” hereinafter) having a high refractive index between a projection lens and a sample has been proposed. In addition, EUV lithography that performs exposure by using ultraviolet rays having a shorter wavelength (13.5 nm) has also been proposed.
However, in the current circumstances, it is very difficult to find out a resist composition necessary for forming a pattern that has an excellent performance overall, and an appropriate combination of a developer, a rinsing liquid, and the like. Particularly, as a resolution line width of a resist is increasingly miniaturized, the resolving power, a roughness performance of a line pattern, and development time dependency are required to be improved.
In recent years, a pattern forming method that uses a developer containing an organic solvent has been undergoing development (for example, see JP2008-281975A and JP2008-292975A). For example, JP2008-292975A discloses a pattern forming method that includes coating a resist composition of which the solubility in an alkaline developer increases and the solubility in an organic solvent developer decreases when the composition is irradiated with actinic rays or radiations onto a substrate, exposing, and developing using an organic solvent developer. According to this method, a fine pattern can be formed stably.
However, regarding the above-described composition, the resolving power, the roughness performance, and the development time dependency are required to be further improved.